Summary

Introduction

Over time, people encounter different dimensions of proxemics in everyday life, such as in face-to-face communication while discussing ongoing work with colleagues, in an elevator with strangers as private space is suspended, or at home with their families. In disciplines like architecture and interior design, knowledge about proxemics has been used for decades to model use of space for face-to-face interactions, urban planning, and environmental design. In human-computer interaction (HCI) and human-robot interaction (HRI), the use of proxemics is fairly new, and both disciplines recently began employing proxemics and related theories and models (e.g., Hall's theory of proxemics in his book, "The Hidden Dimension" [2]) to design new interaction concepts that act on proxemics features. Several recent designs explore the use of human body position, orientation, and movement for implicit interaction with large displays, supporting collaboration, and to control and communicate with robots. This research is facilitated by the operationalization of proxemics for ubiquitous computing [16], toolkits to track proxemics [7,8,9] and new paradigms such as reality-based interaction (RBI) [4] or Blended Interaction [6] that take a fresh look at the role of the user's body and the environment in HCI. However, work on understanding how proxemics can be used for HCI (and HRI) has only just begun (e.g., Proxemic Interactions [1]).

Goals and Structure

In the seminar, we used Greenberg et al.'s dimensions on Proxemic Interactions [1] and Pedersen et al.'s Egocentric Interaction Paradigm [11] as starting points. These theories are based on findings regarding how humans perceive proxemics; therefore, they might be incomplete, particularly since human perception is much more subtle, gradual, and less discrete than illustrated in Hall's reaction bubbles (proxemic zones [2]). In addition, these discrete zones cope with only the physical features (perception of interpersonal distance). Other features, such as psychological and psychophysical features, have not yet been considered in HCI. However, these features are perceptible by human sensors (olfaction, equilibrioception, and thermoception). Current theories neither give guidelines nor provide sufficient methods for "good" or "bad" designs for systems employing proxemics.

We thought the time was right for bringing researchers with different backgrounds and experiences together to map out the important questions that remain unanswered and to generate ideas for developing an agenda for future research on proxemics in HCI.

The structure of the seminar was based on the four pillars technology, application, vision, and theory that were equally exposed in seminar activities. The forum held 29 attendees with multidisciplinary backgrounds from research institutes in Canada, Denmark, England, Switzerland, Australia, France, Belgium, and Germany. We achieved productive and critical reflections and prospects on proxemics in HCI by letting experts from their respective fields work on a shared vision and theory. We selected the attendees to ensure an equal distribution of expertise across the four pillars.

The diversified program allowed attendees to introduce themselves and their work in brief presentations and offered one impulse keynote given by Saul Greenberg and Nicolai Marquardt. Greenberg and Marquardt coined the term Proxemic Interactions and decisively influenced the application of proxemics in HCI. We also provided ample time for discussions, breakout sessions, and creative work addressing concepts such as:

Intelligibility of Proxemic Interactions

Users' options to opt-in or opt-out

The "dark side" of Proxemic Interactions

The meaning of physical space

How image schemas [3] can be used to brainstorm innovative proxemic systems

Ad-Hoc proxemics

Including everyday entities in proxemic systems

Throughout the entire seminar, attendees were encouraged to write down their questions, ideas, and comments. These materials were collected and posted to one of the four pillars on a pin board for the purpose of inspiring breakout groups and ad lib collaboration. The breakout session proposed by the group centered around open problems and challenges within proxemic interactions, which was then discussed in each session.

Technology

In recent years, emerging technology has changed the interaction between human and computer. For instance, smartphones and tablets have entered our daily life. More of such novel post-WIMP technologies will be available in the foreseeable future and ultimately define how we interact in physical spaces. Interaction might take place across device boundaries on (multiple) public [15], large and private, mobile, and tangible displays [13]. It might involve collaboration of co-located users around interactive tabletops [7], in front of large vertical screens [5], or on rollout displays [14]. It might be based on non-traditional, post-WIMP interaction styles, such as pen-based [10], multi-touch, and tangible user interfaces. Or, it might provide new forms of functionality beyond the traditional WIMP model of applications by tracking users' spatial location and movements for navigation within large, digital information spaces [12]. Attendees discussed existing technologies that allow people-to-people, people-to-object, and object-to-object proxemics relations tracking, as well as improvements on tracking reliability using sensor fusion.

Application

Seminar attendees discussed the "light" and "dark" side of Proxemic Interactions. Until now, research has focused on the benefits of these interactions; however, they bear risks. We all can imagine how advertisement would change if it becomes possible to show customized ads according to our online shopping profiles while we are walking on public streets or in shopping malls. During the seminar, participants discussed what types of applications would best showcase the benefit of proxemics and avoid the risks that arise when systems are able to track and identify people. Part of this discussion included brainstorming opt-in or opt-out functions for proxemics-aware systems so that users can remain in control of these systems.

Vision

In its past, HCI has benefited from ambitious visions of future interaction such as Apple's Knowledge Navigator or Mark Weiser's "A day in the life of Sal" [16]. Although visions are not always helpful and can lead in wrong directions, we believe that a new overarching vision of future Proxemic Interactions can help inspire ongoing research and thrive in coming generations. This vision is intended to inform researchers, designers, and laymen alike. For researchers, a vision can serve to illustrate research goals, trigger new research directions, and create awareness for as yet un-reflected assumptions in our field. For designers, visions help to present concepts and technologies as a part of a believable scenario -- and not only in the isolation of conference papers. Furthermore, visions serve to fascinate and inspire laymen, who prefer to learn about future technologies from narrations instead of purely technical publications. The seminar aimed at creating a unified vision of Proxemic Interactions based on the individual contributions and experiences of the seminar attendees. Current and past visions have been discussed in plenum and breakout groups.

Theory

In the light of the countless variants and dynamics of post-WIMP interaction, traditional collections of design guidelines or "golden rules" cannot provide enough guidance about "good" or "bad" designs. Instead, we need better theories and models of human cognition to be able to understand and classify designs of Proxemic Interactions and to predict their appropriateness. We wanted to understand how physical, psychological and psychophysical features collate and can be transferred into a coherent theory of proxemics in HCI and how to give guidelines or provide sufficient methods for "good" or "bad" designs. Therefore, we had to:

Better understand proxemics in HCI to develop such methods

Discuss the open question: to what extent can proxemics leverage or constrain human-computer interaction?

Conclusion

The Dagstuhl Seminar 13452 offered a fantastic forum for established researchers and practitioners at a comfortable place. We framed and discussed research questions and worked together on a unifying theory for Proxemics in Human-Computer Interaction. Applications for Proxemic Interactions were sketched out and critically reflected in the light of the "dark side" of proxemics. We also discussed how we can learn from related fields and how they can profit from proxemics in HCI.

The seminar can be seen as a good starting point to identify the role of Proxemics in Human-Computer Interaction. However, it still remains an open research area and its place in HCI needs to be better understood.